Caffeine is arguably the world’s most studied drug, but new research by Stellenbosch University investigated its differing effects on men and women.
Twenty-six triathletes (14 men, 12 women) faced two identical Olympic-distance triathlons 14 days apart in South Africa. One hour before the start of each race, they either took a placebo or a capsule containing 6mg of caffeine per kilogram of bodyweight.
On average, the men raced 1.7% faster after the caffeine, compared to 0.9% for the women. The majority of physiological markers remained similar, although cortisol was much higher in the men. The stress hormone rises during intense exercise, suggesting that the men could dig slightly deeper when racing on caffeine.
The authors speculated that this could be due to a greater impact on men’s central nervous system. They also noted that the female subjects were more habituated to caffeine, which lessened its impact. The researchers concluded that both genders would benefit from 6mg/kg body mass of caffeine, 45-60mins before a race.